Longitude
Collier's New Encyclopedia (1921)
in astronomy, the disof Bull Run. In 1862 he was made tance in degrees reckoned along the eclip- Major-General, and earned great celebtic from the spring equinox to a circle at rity under General Lee, in the campaigns right angles to it passing through the against Generals Pope, McClellan, and heavenly body whose longitude is re- Burnside. After the battle of Frederquired. A star situated directly in the icksburg, General Longstreet was given line between the pole of the ecliptic and the command of a corps, with the rank the vernal equinox has no longitude. In of Lieutenant-General. With this force place of celestial longitudes right ascenhe took an active and distinguished part sions are now generally noted. In geogin the battles of Chancellorsville, Gettysraphy, distance east or west on the surburg, and Chickamauga. In the battle face of the globe. The longitude of a of the Wilderness, General Longstreet place is the arc of the equator intercepted was dangerously wounded. After the between the meridian of the place and a fall of Richmond he surrendered, and meridian passing through some other lived in comparative retirement till 1869, place from which longitude is reckoned. when he was appointed Supervisor of Customs at New Orleans. Later he was made Minister to Turkey, and United States Marshal for the District of ditenco haowban GEN. JAMES LONGSTREET Georgia. In 1897 he was appointed United States Commissioner of Railroads. He published "From Manassas to Appomattox" (1904). He died near Gainesville, Ga., Jan. 2, 1904.
What Has Changed in the Last Century
The definition Collier's gave in 1921 still holds: longitude is the arc of the equator between a place's meridian and a reference meridian. What has changed is that reference and the way the angle is found. Collier's could only say longitude is reckoned from "some other place" — by then most nations followed the 1884 Washington conference in using Greenwich, and today the world uses the IERS Reference Meridian, a satellite-derived line about 100 metres east of the old Airy transit circle at Greenwich. The chronometers, lunar observations and telegraph and radio time signals that fixed longitude in 1921 have been replaced by GPS and its rivals, which give any phone a position to a few metres. Collier's remark that celestial longitudes have given way to right ascension also still stands, though ecliptic longitude remains standard for planets, comets and asteroids.
Written for this edition, 2026.